Chicago-based Encyclopaedia Britannica, which shelved its venerable print edition in favor of a digital-only version more than two years ago, is looking to reclaim its legacy as the household reference of choice.

The 246-year-old, privately held company is shifting its virtual encyclopedia toward a free, advertising-supported model, believing it is poised to click with a new generation of online knowledge consumers.

"I think that most people in the consumer space would prefer to use Britannica to many other alternatives," said Jorge Cauz, 52, Encyclopaedia Britannica's president. "Whenever Britannica appears on search engines, we have a pretty amazing click-through rate."

Once the undisputed king of reference libraries, with armies of door-to-door salesmen peddling the expensive multivolume sets to families across the globe, Britannica has struggled to find its place in the digital age, where user-generated Wikipedia offers something on just about everything for free.

Hoping to boost site traffic and grow advertising revenue, Cauz has opened about half of Britannica's online database to the public at no charge. Two years ago, 80 percent of the articles were behind a pay wall, accessible only to subscribers.

Some 50,000 households pay $70 annually and an additional 450,000 get full access through distribution partners such as telecom companies and Internet providers, a subscriber base that has remained stable despite the chipping away of the pay wall, Cauz said. Meanwhile, online traffic has more than doubled, and advertising growth has reduced dependence on user fees. Subscriptions now account for 75 percent of Britannica.com's revenue, down from 95 percent two years ago.

Like many traditional publishers, Britannica is finding that what worked on paper doesn't necessarily succeed online. The push-pull between advertising and subscription revenue, though, is nothing new, according to media analyst Ken Doctor.

"For consumer publishing businesses in general, they've always balanced circulation revenue on one hand and advertising on the other, and tried to optimize both," Doctor said.

Advertising will generate about $13 million this year for the Britannica consumer websites, up 70 percent since 2010. Its digital portfolio includes Britannica.com, Merriam-Webster.com and more than 20 other reference websites, and the revenue upside is exponential, Cauz said.

"We think that there are hundreds and hundreds of millions of dollars of advertising potential that Britannica could tackle, if we were to have a very different business model," Cauz said. "It doesn't mean that we are going to be able to do that overnight. It means that we are going to be experimenting to be able to capture a place in the consumer space again."

Britannica.com is on track for 12 million visitors in September, up from 4.7 million during the same month in 2012, executives said. Back-to-school visits are expected to ramp up in October, but the company goes beyond homework help to drive up traffic, employing such unabashed click-bait techniques as photo galleries, quizzes and "listicles," which combine lists with articles.

"You have to put out bait to get sampling, and many, many page views to fuel a digital advertising business," Doctor said.

The hard sell, digital or otherwise, is an integral part of Britannica's history.

Founded in Scotland, Britannica has been headquartered in Chicago since 1935, when it was under the ownership of Sears. Marketed door to door for generations, it sold more than 100,000 printed sets as recently as 1990, its best year ever, when it generated $650 million in revenue.

Print sales fell precipitously in the face of fast-evolving digital platforms. The company was sold in late 1995 to Swiss investor Jacob Safra, who ended its door-to-door sales operation, cutting loose about 2,500 contract salespeople worldwide, Cauz said.

With the launch of Wikipedia in 2001, the writing was on the wall for Encyclopaedia Britannica's pricey leather-bound sets. Cauz, a native of Mexico City with an MBA from Northwestern University, took the helm in 2003, shifting the company's focus from consumer sales to the $10 billion U.S. educational market. He closed the book for good on its printed encyclopedia in 2012.

The global educational business now represents 90 percent of the company's revenues and virtually all of its profit. Key products include Britannica School, ImageQuest and "Pathways: Science," with an assortment of offerings that serve students from prekindergarten through college. Total revenues are up nearly 10 percent this year, Cauz said.

Encyclopaedia Britannica employs 500 people worldwide, with 210 housed in expansive riverfront offices at 325 N. LaSalle St., a site visited by many Chicagoans in its previous incarnation as Traffic Court. User interface, curriculum and technology specialists abound as the company's diversified business model evolves.

Though the company itself is in the black, Britannica.com is barely breaking even, Cauz said. The educational business allows him leverage to tweak the online encyclopedia, and the patience to nurture it, as he seeks to increase its reach. That means taking back business from Wikipedia, a free encyclopedia website built and maintained by users, which dominates the digital reference space.

Britannica is a decided underdog in the digital world. Wikipedia has nearly 4.6 million English language articles, compared with 106,000 for Britannica.

Where Britannica trumps Wikipedia is through a "rigorous editorial process," Cauz said. Like Wikipedia, users and scholars contribute to the database, but each article is professionally vetted by Britannica, enabling students and dilettantes alike to speak with authority on any given subject.

"I think the honeymoon for 'everything goes' is over," Cauz said. "I think people are understanding that even though digital technologies are great ways of creating and disseminating content, knowledge and scholarship are not democracies. There are people that know better, and the challenge is how to make that knowledge more efficient and make that knowledge reach many, many more people."

Britannica has added some 2,900 new articles and revised 7 million words this year, Cauz said. The site also includes some 5,000 videos. Though the database continues to grow, its breadth won't soon rival Wikipedia's, which details porn stars to Pokemon, and even includes what Cauz describes as an "inaccurate" entry on himself.

On core subject matters, Britannica covers much of the same turf as Wikipedia. Finding its articles, though, can be a little more challenging, something Cauz readily acknowledges.

"We need more visibility," he said. "We need to be able to attract more people. We need to be more present on search engines."

A Google search for Abraham Lincoln, for example, came up with nearly 3.5 million results, with a Wikipedia entry at the top of Page 1. The Britannica entry was near the middle of Page 2, well behind such esteemed sites as BrainyQuote.com. A click on the Britannica link revealed a full, free, media-rich article.

The Britannica page also featured video and banner ads for everything from Home Depot to a Chicago law office. Most are placed by a real-time bidding network, but an in-house staff also sells advertising. Unlike some publishers, the company has yet to delve into native advertising — paid online editorial content designed to lure readers, a line Cauz is not ready to cross.

Almost everything else is on the table for the virtual encyclopedia.

"If Britannica becomes an anchor on the Web for people that are wanting to learn and know, we can do a lot of things with this brand," Cauz said. "It can be very, very profitable."